>> i still watch the reruns. >> thanks for joining us. lester holt is next with nightly news. >> bye, folks. tonight, iran releases americans. dramatic images of the moment the navy boats were seized. new details on the efforts to free them and the apology one american made on a iranian state tv. fighting words. donald trump hits back at the rising republican star who took him on and opened a new rift in the party. and hillary clinton on thettack as pressure mounts for her campaign. el chapo's texts. new insight into his time on the run. flirtatious messages between the drug kingpin and this actress, calling her beautiful and planning a secret rendezvous with tequila and dancing. and train tragedy. deadly crashes that could have been prevented by technology that has

been around for years. so why are so many trains around the country still running without it? "nightly news" begins right now. good evening. ten american sailors held by iran are safe tonight. freed earlier today. quickly sparing another major international crisis. but not the humiliation of this sight of american navy crewmen, hands above their heads, boats and weapons displayed on iranian television and around the world. tonight we learned more about how they ended up in iranian hands and how two long, bitter adversaries managed to successfully extinguish this flash point before it could fully erupt. nbc's jim miklaszewski from the pentagon. >> reporter: the images are jarring. the ten american sailors on their knees, hands clasped behind their heads on the deck of their own u.s. navy vessel, surrounded by armed iranian military. the video shot by the iranians and aired on iranian-state television. once on shore, more videos of the

americans, nine men and one woman in confinement and sharing a meal in show they were well treated. one of the sailors apologized for entering iranian territorial waters. >> it was a mistake that was our fault and we apologize for our mistake. >> it is unclear what were the circumstances when the video was taken. u.s. military officials call the video pure propaganda. the u.s. sailors were released early today. the two boats returned to the u.s. navy. secretary of state john kerry pulled out all diplomatic stops to personally negotiate the americans' release. calling iran's foreign minister at least five times over ten hours, according to a senior state department official. >> i'm appreciative for the quick and appropriate response of the iranian authorities. >> reporter: iran's foreign minister tweeted, happy to see dialogue and respect. let's learn from the latest example. but foreign policy experts warn in many respects that iran is a dangerous adversary.

>> there are things they are doing in the region that are not helpful at all. they have american citizens detained in tehran which is of great concern to us. >> reporter: today the revolutionary guard acknowledged they found no evidence the americans were spying. and now that they have been released, the navy should find out why they drifted in iranian territorial waters where they were detained. tonight those ten american sailors are at an undisclosed location in the persian gulf. where they will get a full physical and mental health exam. the exact same treatment given to returning p.o.w. and hostages, lester. >> jim miklaszewski, thanks. this time last night we were in the nation's capital for the president's final state of the union address. the president striking a more optimistic tone than in years past but raising questions he says americans need to answer about the economy, technology, security and the rancor in our political system. one of the biggest regrets he said was

the political divide only grew during his time in office. and he spoke about what it will take to attain the future all americans want. >> but it will only happen if we work together. it will only happen if we can have rational, constructive debates. it will only happen if we fix our politics. >> while the president didn't mention donald trump by name, it wasn't hard to figure out who he had in mind with some of his more pointed remarks last night. and much to the surprise of many, trump again surfaced much the same way in the formal republican response to the president's speech. as hallie jackson reports, one of the gop rising stars used her national platform to take her party's front-runner to task. >> reporter: even when he's not supposed to be in the spotlight, donald trump still is. nikki haley's republican response rebuking not just

president obama but her own party's presidential front-runner. >> during anxious times it could be tempting to follow the siren call of the angriest voices. we must resist that temptation. >> in that context, you are referring to donald trump, correct? >> he was one of them, yes. mr. trump has definitely contributed to what i think is irresponsible talk. >> reporter: trump now hitting her back. >> i'm very strong on illegal immigration, she's weak on illegal immigration. maybe it will turn out to be bad for her because people know where i stand and you see the numbers. >> reporter: governor haley and house speaker paul ryan represent what some establishment republicans think the gop should be, more diverse. more inclusive. what the gop has is trump, leading the pack and mobilizing a new base of support for the party. even as the establishment strikes back and his closest rival fights back. >> donald comes from

new york and he embodies new york values. and listen, the donald seems to be a little bit rattled. >> reporter: trump keeping up birther attacks on cruz, and 15% of republicans now saying it bothers them he was born in canada to an american mother. >> that is a big factor. >> reporter: the rivals now fighting for first in iowa. leaving little room for the establishment candidates. >> the establishment is being left out entirely for the first time in history. are we going to be able to pull everyone together. >> reporter: the battle lines drawn and the gop civil war, the fight for the party's future. haley is standing by her speech even as she comes under fire from leaders on the conservative right. striking, given just a few years ago she was seen as a tea party crusader, a star in the making in that wing of the party. >> hallie jackson, thank you. the race is growing contentious from the democratic side with four days until the next debate which will air here on nbc, the latest polls show troubling news for hillary clinton. with her numbers slipping, clinton and bernie sanders are stepping up attacks on

each other. we get more from nbc's kristen welker. >> reporter: hillary clinton and bernie sanders escalating the sniping today. clinton firing the first volley, repeating her toughest attacks on health care and guns. >> senator sanders has been a reliable vote for the gun lobby and i have been standing against them for a long time. >> reporter: on msnbc today, sanders punched back. >> to say i'm a supporter of the nra is a mean-spirited and unfair and inaccurate statement. >> reporter: her ramped up rhetoric comes with the democrats locked in an unexpected nail-biter. a new national poll showing her lead tumbling. she still tops sanders but only by seven points, 48% to 41%, a sharp decline from her 20-point lead last month. on the "today" show today she downplayed the numbers. >> no, i'm not nervous at all. i'm working hard. and i intend to keep working as hard as i can.

>> reporter: so why are more and more democrats feeling the burn? sanders, a self-described democratic socialist, could be tapping into voters' desire for an anti-establishment candidate. that hunger particularly strong among younger voters under 45 who favor sanders nearly two to one. >> i think that bernie sanders aligns more with my views and i think we should be voting for the person who will be best in the white house. >> reporter: donald trump may have help erode some of clinton's support, reminding voters of her husband's transgressions when he was in office. >> i'm so proud my husband is on the campaign trail. in new hampshire and in iowa in the last week. >> reporter: and today president clinton returned, where he brushed aside the declining polling numbers, saying a heated debate is good. a sign the clinton campaign may be getting jittery, for the second time this week the aides held

conference calls with reports bashing braes. he hasn't said how he will pay for the universal health care plan. an aide telling me those details are coming soon. lester. >> kristen welker, tonight, thank you. there are new questions about el chapo time on the run. just released text messages shows his infatuation with the same actress that helped arrange his interview with actor sean penn. we get details from jacob rascon in mexico. >> reporter: it plays like the telenovella that made her famous. a larger than lyft cartel leader on the run, smitten with a megastar, planning secret meetings in the mountains. in a series of text messages intercepted by the mexico government, el chapo guzman reaches out to del castillo. "i'm very eager to meet and become great friends. you are the best in

the world. i will take care of absolutely everything." "it is so moving that you say you will take care of me," she replies. "no one has ever taken care of me. thank you. i am free next weekend." later guzman seemed to obsess over which cell phone to buy her as a surprise. preferably a pink phone. and writing to his atrnmes we will drink tequila and dance. tell her just like that. as for meeting actor sean penn, el chapo didn't know who he was and told his attorney, i'm looking him up on the internet. late today, she tweeted to fans, thanks for your support. inside the federal prison behind me el chapo is again on the move, this time by mexican authorities who have transferred him between cells eight times since he arrived here last friday. desperately trying to prevent yet another embarrassing escape.

jacob rascon, nbc news, mexico. a warning today from the ntsb that without a major safety upgrade to the nation's rail lines, we risk another catastrophic crash. investigators say a system called ptc, for positive train control, could have prevented several deadly crashes. but while amtrak has rolled it out on many trains, tom costello reports that other railroads are lagging far behind. >> reporter: it happened last may 12th. eight passengers died, 200 injured when a speeding amtrak train derailed north of philadelphia. 2013, four dead when a speedy metro-north trail derailed in the bronx. 2008, 25 dead after a metro link train blew a stop signal in chatsworth, california. while the technology was available to prevent those accidents, none of the trains had it. >> it says you are going too fast. you are at 90 miles per hour. >> it is slowing down for you. >> it just took over control of the train for me.

>> reporter: at the amtrak training center in delaware, we saw how positive train control works. now, eight months after the philly crash, amtrak has finished equipping the entire northeast corridor. with transponders in the track's monitor every train and slam on the brakes if necessary. but ptc is only in place in the northeast and areas around los angeles. the rest of the railroads are owned by freightlines which complained about the technology cost and complexity. so congress has given them more time, until 2018, to get ptc up and running. not good enough, says safety experts. >> every day that ptc is not in place, we run the risk of another amtrak crash in philadelphia, or another bronx crash. >> reporter: in essence, the technology is about trying to remove human error as a factor by forcing the train to abide by speed limits and stop signals. >> amtrak said it would have saved lives in philadelphia. >> we are going to keep moving as quickly

as we can to make a safer -- a damn safe railroad safer. >> reporter: still no word from ntsb on why the amtrak train was speeding in philly. but the high-speed safety fix is on a slow roll-out. tom costello, nbc news, delaware. >> a dismal day on wall street. the dow dropping nearly 365 points. the nasdaq plunging more than 3 prs. still ahead, president obama vowing to cure cancer. >> to you to play for and pay for tonight's $1 poin 5 jackpot.

let's explore now a very ambitious idea announced by the president in his state of the union. a commitment to cure cancer in the way we committed to reaching the moon in the '60s. it will be led by joe biden and aimed at ending the disease that killed the vice president's son and 600,000 other americans every year. nbc's anne thompson

explains what the new national effort could mean for the millions of americans battling cancer. >> reporter: the moon shot is the symbol of american ambition and achievement. now vice president joe biden will lead a similar effort to cure cancer. for biden, this is personal. choking up, talking to stephen colbert about his son beau, who died of brain cancer. >> my son was better than me. and he was better than me in almost every way. >> reporter: the vice president has two goals. increase spending on research and increase collaboration. just this week, a group of drug companies and researchers announced they would work together to find better treatments. last week biden's staff met with the president of the american association for cancer research. >> how close are we to curing cancer? >> we could really decrease by a lot the number of patients that die from cancer. so i think this ought

to be our decade. >> dr. baselga credits biden with getting the first budget increase in a decade, an extra $264 million, a 5% jump. the american cancer society's dr. otis brawley said they need sustained funding and all patients need access to best care. >> 20% or more women with breast cancer get less than optimal breast cancer treatment. those are some of the things we could fix right now and fix very quickly. >> reporter: emily whitehead is now 10 years old because of a breakthrough to treat her leukemia at the university of pennsylvania and children's hospital of philadelphia. friday she will meet the vice president, a living example of what is possible. anne thompson, nbc news, new york. when we come back, they'll be there for you. the joy in l.a. and the anger in st. louis.

big news in the sports world. the nfl gave the go 0-ahead for the st. louis rams to move back to los angeles. it could have consequences far beyond the field. >> reporter: for the st. louis rams, after 21 years in st. louis, rams' fans are hanging up their jerseys. >> i'm very disappointed in the nfl. >> reporter: the owner says the cash-strapped city could not afford a new stadium. the team headed to los angeles where they played for nearly half a century. >> it is bittersweet. we understand the emotions involved of our fans. >> reporter: the rams

will kick off their third three seasons at the l.a. coliseum until their new home this $1.8 billion stadium and entertainment stadium is built in englewood, ten miles from downtown los angeles. >> this will increase not only property values and employment opportunities, but increased community pride. >> reporter: after 55 years in san diego, chargers have the options to join the rams. with the welcome wagon out, football is back in l.a. miguel almaguer, nbc news, los angeles. >> why so many of us keep going after that record powerball jackpot even when we know how hard it is to win. warned -- to watch their back.

===jess vo=== plus, buried in the dirt for more than 13 hours. tonight -- the plumber tells us about his harrowing ordeal. ===next close=== next. ==take sot== we all take this job knowing that those risks are those. we come wo knowing those risks are tre. finally tonight, consider this. just a short time from now america will either have a new billionaire, or the powerball jackpot will roll over to another record. $2 billion. our kevin tibbles explains to us why our minds keep driving us to play even when we know the odds are against us. >> reporter: powerball lunacy is sweeping the nation. the symptoms --

an increased hope rate and crossed fingers. so we went to renowned behavioral psychologist dr. frank farley to analyze. >> why do we buy these things? >> turns out we americans suffer from a new condition. >> type t., for thrill, type t. personality. >> it is a thrill, man. i love it. >> reporter: that is why we're wearing out the machines, because for $2 a pop we could all be eternal optimists. >> this is it. this is going to change my life forever. >> you have to have a little hope and drive. >> if you don't have hope, what do you have? >> $2. >> and then there is the mount everest effect. why play? because it is there. >> this is the mount everest of lotteries. it is too big to ignore. >> i want to be a billionaire. >> reporter: and heck, when you see everyone else lining up to play, it becomes contagious.

>> fomo, fear of missing out. this is the newest fear in the armament of the psychologist. for us to study. >> because everybody se is buying a ticket? >> pretty much. >> reporter: there is another less scientific explanation. >> number one on my list is fun. >> reporter: and a few other reasons too. but for now the best prescription, stay optimistic until the powerball drops. kevin tibbles, nbc news, philadelphia. >> i don't know about you, but i feel better. th will do it for us on a wednesday night. i'm lester holt. for all of us at nbc news, good night and good luck.

we all take this job knowing that those risks are there and we come to work knowing that those risks are there. >> off-duty officers being targeted. the serious warning a police department is sending to officers across the bay area. good evening. thanks for being with us. >> in the line of fire while on the job and now off duty as well. several bay area police departments are sending out a warning to officers. stay alert at all times. that cryptic call for care after several attacks on officers while off duty.

how many times are we talking about these attacks? >> reporter: two times, three officers. i did receive this internal police document from a source. while i can't share with you what's inside the document to protect officer safety, i can tell you the recent attacks are drawing a lot of concern for officer safety in and out of uniform. they turn in their patrol cars at the end of every shift and go home. but the dangers of their job have been following some officers home. >> we take this job knowing that those risks are there. >> reporter: this detective says his deputies were not involved in the recent after work attacks, but their office nonetheless alerted its deputies. >> it's a reminder for us to always be vigilant. we have to -- we go to training, our experiencelw